int i, j, c;
int c0 = 0;
void setup() {
  size(640,640);
  textSize(32);
  for (i=1; i<16; i++) {
    j = i*height/16;
    line(0,j,width,j);
    line(j,0,j,height);
  }
}
void draw() {
  i = int(map(mouseX,0,width,0,16));
  j = int(map(mouseY,0,height,0,16));
  c = j*16+i;
  if (c != c0) {
    text(char(c),map(i,0,16,0,width), (j+1)*height/16);
    println(c+" ("+char(c)+") "+i+","+j);
    c0 = c;
  }
}
